U.S. patent application number 10/509010 was filed with the patent office on 2005-07-21 for engine for converting thermal energy to stored energy.
Invention is credited to Lewellin, Richard Laurance.
Application Number | 20050155347 10/509010 |
Document ID | / |
Family ID | 3834972 |
Filed Date | 2005-07-21 |
United States Patent
Application |
20050155347 |
Kind Code |
A1 |
Lewellin, Richard Laurance |
July 21, 2005 |
Engine for converting thermal energy to stored energy
Abstract
The engine for converting thermal energy to stored fluid energy
includes expansion cylinders (61a-f) with expansion chambers
(62a-f) and flexible membranes (63a-f). Heating and cooling of
working fluid inside the cylinders (61a-f) is carried out by fluid
supply lines (73, 71) communicating with external heat resources
and sinks. Pressure accumulator (66a) is adapted to store a
pressurised fluid (64a-f), such as hydraulic oil, from the
individual cylinders (61a-f). In use, this pressurised fluid is
delivered at an elevated and above a minimum threshold pressure
level, irrespective of the irregularities of the movement of the
expansion cylinders (61a-f).
Inventors: |
Lewellin, Richard Laurance;
(Somerville, AU) |
Correspondence
Address: |
TRASK BRITT
P.O. BOX 2550
SALT LAKE CITY
UT
84110
US
|
Family ID: |
3834972 |
Appl. No.: |
10/509010 |
Filed: |
September 24, 2004 |
PCT Filed: |
March 27, 2003 |
PCT NO: |
PCT/AU03/00380 |
Current U.S.
Class: |
60/508 |
Current CPC
Class: |
F03G 6/00 20130101; Y02E
10/46 20130101; F01K 25/02 20130101 |
Class at
Publication: |
060/508 |
International
Class: |
F01B 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 27, 2002 |
AU |
PS 1382 |
Claims
1. An engine for converting thermal energy to stored energy, the
engine including: (a) a thermal energy converter including an
expansion chamber which is adapted to vary in volume by the
movement of a movable wall forming one part of said expansion
chamber, said expansion chamber capable of performing an
expansion-contraction cycle; (b) a working fluid in said expansion
chamber which expands upon being heated whereby to displace the
movable wall in a first direction to expand the volume of said
expansion chamber and contracts upon being cooled to displace the
movable wall in an opposed direction to reduce the volume of said
expansion chamber; (c) a temperature modifier adapted to draw on:
(i) a heat source to heat the working fluid to expand the volume of
the expansion chamber by the displacement of the expansion wall to
increase the volume of said expansion chamber as a first expansion
part of said cycle; and (ii) a cooling source to cool the working
fluid to reduce the volume of the expansion chamber and to permit
the return of the movable wall as a second part of said cycle; and
(d) pressure storage means operatively associated with said movable
wall and adapted to deliver pressurised fluid to an accumulator
means, said accumulator means for storing said pressurised fluid at
an elevated pressure, wherein said accumulator means is capable of
being bled of said pressurised fluid at a predetermined rate such
that the accumulated said elevated pressure is maintained at a
minimum threshold level, irrespective of the irregularity of the
movement of said movable wall.
2. An engine according to claim 1, wherein said heat source is an
external source of fluid with a temperature above 39C.
3. An engine according to claim 2, wherein said external source of
fluid is a by-product or waste product of an industrial or
mechanical process.
4. An engine according to claim 1, wherein the regularity and speed
of the movement of said movable wall is influenced by the
difference between the temperatures of said heating and cooling
sources and the stage of said cycle.
5. An engine according to claim 1, wherein a first predetermined
dwell time precedes each expansion part of said cycle.
6. An engine according to claim 1, wherein a second predetermined
dwell time precedes each contraction part of said cycle.
7. An engine according to claim 1, wherein said pressure storage
means includes a storage piston operatively coupled to said movable
wall and further includes pressure intensification means whereby
the surface area of said movable wall is greater than the surface
area of said storage piston.
8. An engine according to claim 1, wherein said engine includes a
plurality of thermal energy converters arranged in parallel to
charge said accumulator means with said pressurised fluid.
9. An engine according to claim 8, wherein said plurality of
thermal energy converters operate independently of one another.
10. An engine according to claim 8, wherein the operation of said
plurality of thermal energy converters is coordinated to deliver a
relatively consistent supply of pressurised fluid to said
accumulator means.
11. An engine according to claim 10, wherein said plurality of
thermal energy converters are controlled by pressure switch means
to determine selectively the heating or cooling of said working
fluid.
12. An engine according to claim 10, wherein each said movable wall
of said plurality of thermal energy converters is in the form of a
converter piston and is mechanically linked by a rocker arrangement
to determine selectively the heating or cooling of said working
fluid.
13. An engine according to claim 12, wherein said heating and
cooling sources are sources of hot and cold fluid, respectively,
and the delivery of said hot and cold fluid to said plurality of
thermal energy converters is controlled by valve switching means to
determine selectively the heating or cooling of said working fluid
in each said converter.
14. An engine according to claim 1, wherein said working fluid is a
refrigerant.
15. An engine according to claim 1, wherein said pressurised fluid
is a hydraulic oil.
16. An engine according to claim 1, wherein said engine is adapted
to power work output means by the process of bleeding said
pressurised fluid to drive a generator or an alternator.
17. An engine according to claim 16, wherein said alternator
generates alternating current suitable for powering work output
means in the form of appliances adapted to be powered by mains
electricity.
18. An engine according to claim 1, wherein said movable wall is a
flexible membrane.
19. An engine according to claim 18, wherein said pressure storage
means forms part of said thermal energy converter and said
expansion chamber is one compartment of said thermal energy
converter separated from said pressure storage means by said
movable wall.
20. An engine according to claim 5, wherein a second predetermined
dwell time precedes each contraction part of said cycle.
Description
FIELD OF INVENTION
[0001] This invention relates to an engine for converting thermal
energy to stored energy.
BACKGROUND ART
[0002] Methods of performing useful work by utilising sources of
heat that are external to a working apparatus have been described.
However, there are available sources of heat energy that have
either not been effectively utilised to perform useful work.
[0003] It would bedesirable to use relatively low temperature
sources of heat energy or to utilise heat energy from sources that
is presently being wasted. However, it will be appreciated that the
invention is not limited to energy sources of low temperature.
Fluid with temperatures of up to 100.degree. C. and beyond could be
utilised by the invention. The temperature of the energy source may
determine the type of thermal energy converter, such as all whether
an evaporator or condensor may be used.
[0004] For example, solar radiation can be used to readily heat
water to modest temperatures such as 40.degree. C.-60.degree. C.
and it would be advantageous if such heat energy could be used to
perform useful work. Heated water or heated water vapour can be
obtained from hydrothermal sources. For example, bore water
extracted from ground aquifers and used for irrigation or for
drinking water for stock or for domestic use in remote locations is
often at all elevated temperature and it would be beneficial if the
heat energy of such water could be reduced and utilised to perform
useful work. Also there are many possible sources of heat energy
that are presently unutilised or underutilised such as heat energy
in exhaust gases or particles such as smoke: (a) from internal
combustion engines, such as engines driving generators or even
being used in vehicles and (b) discharged from industrial plant and
equipment.
STATEMENT OF INVENTION
[0005] An engine for converting thermal energy to stored energy,
the engine including:
[0006] (a) a thermal energy converter including an expansion
chamber which is adapted to vary in volume by the movement of a
movable wall forming one part of the expansion chamber, the
expansion chamber capable of performing an expansion-contraction
cycle;
[0007] (b) a working fluid in the expansion chamber which expands
upon being heated whereby to displace the movable wall in a first
direction to expand the volume of the expansion chamber and
contracts upon being cooled to displace the movable wall in an
opposed direction to reduce the volume of the expansion
chamber;
[0008] (c) a temperature modifier adapted to draw on:
[0009] (i) a heat source to heat the working fluid to expand the
volume of the expansion chamber by the displacement of the
expansion wall to increase the volume of the expansion chamber as a
first expansion past of the cycle; and
[0010] (ii) a cooling source to cool the working fluid to reduce
the volume of the expansion chamber and to peat the return of the
movable wall as a second part of the cycle; and
[0011] (d) pressure storage means operatively associated with the
movable wall and adapted to deliver pressurised fluid to an
accumulator means, the accumulator means for storing the
pressurised fluid at an elevated pressure,
[0012] wherein the accumulator means is capable of being bled of
the pressurised fluid at a predetermined rate such that the
accumulated the elevated pressure is maintained at a minimum
threshold level, irrespective of the irregularity of the movement
of the removable wall.
[0013] The heat source may be an external source of fluid with a
temperature above 39C. The external source of fluid may be a
by-product or waste product of an industrial or mechanical process.
The regularity and speed of the movement of the movable wall may be
influenced by the difference between the temperatures of the
heating and cooling sources and the stage of the cycle. A first
predetermined dwell time may precede each expansion part of the
cycle. A second predetermined dwell time may precede each
contraction part of the cycle. The pressure storage means may
include a storage piston operatively coupled to the movable wall
and may further include pressure intensification means whereby the
surface area of the movable wail is greater than the surface area
of the storage piston.
[0014] The engine may include a plurality of thermal energy
converters arranged in parallel to charge the accumulator means
with the pressurised fluid. The plurality of thermal energy
converters may operate independently of one another. The operation
of the plurality of thermal energy converters may be coordinated to
deliver a relatively consistent supply of pressurised fluid to the
accumulator means. The plurality of thermal energy converters may
be controlled by pressure switch means to determine selectively the
heating or cooling of the working fluid. Each the movable wall of
the plurality of thermal energy converters may be in the form of a
converter piston and may be mechanically linked by a rocker
arrangement to determine selectively the heating or cooling of the
working fluid.
[0015] The heating and cooling sources may be sources of hot and
cold fluid, respectively, and the delivery of the hot and cold
fluid to the plurality of thermal energy converters may be
controlled by valve switching mean to determine selectively the
heating or cooling of the working fluid in each the converter.
[0016] The engine may be adapted to power work output means by the
process of bleeding the pressurized fluid to drive a generator or
an alternator. The alternator may generate alternating current
suitable for powering work output means in the form of appliances
adapted to be powered by mains electricity.
[0017] According to another aspect there is provided an engine
including:
[0018] (a) an expansion chamber having a movable wall so that the
chamber has a variable volume, the chamber containing a working
fluid which increases in pressure and expands upon being heated by
an external heat source so as to move the wall upon being heated
and increase the volume of the chamber and conversely which
contracts upon being cooled so that the wall moves in the opposite
direction to decrease the volume of the chamber;
[0019] (b) pressure storage means, wherein the wall is operative to
charge the pressure storage means whereby to convert the kinetic
energy of the movable wall, to stored energy in the pressure
storage means; and
[0020] (c) controlled work output means, wherein the engine is
adapted to to provide a constant power supply to the controlled
work output means, irrespective of the irregularity of the movement
of the movable wall.
[0021] The expansion chamber may include a cylinder having a piston
movable therein, the piston defining the movable wall of the
chamber. Alternatively, the movable wall may be a diaphragm or
other flexible membrane adapted to expand the expansion chamber
with the expansion of the working fluid.
[0022] The working fluid preferably has a high thermal expansion
co-efficient. The working fluid may be a gas or liquid. Preferably
the working fluid is a Liquid. Even more preferably, the liquid is
a refrigerant. The working fluid may be any suitable material such
as a refrigerant of the kind used in refrigeration and air
conditioning plant, e.g. freon gases, ammonia, isopentanes, AZ20
etc.
[0023] The engine may include fluid heating means for applying heat
from the external source to the working fluid during a heating
cycle of the engine so as to cause the working fluid to expand in
the expansion chamber. The engine may include fluid cooling means
for cooling the working fluid during a cooling cycle commencing
after the heating cycle 90 as to cause contraction of the working
fluid in the expansion chamber.
[0024] The fluid heating means and fluid cooling means may include
a heat exchanger for supplying heat energy to the working fluid and
for extracting heat energy from the working fluid, respectively.
The heat exchanger may be provided with heat energy from the
external source during the heating cycle, e.g. by being supplied
with heated water from solar heat collectors or by thermal ground
water or directly or indirectly with heat from a source of waste
heat energy. Conversely during the cooling cycle, the heat
exchanger may be supplied with a cooling medium such as surface
water from any convenient local source.
[0025] The engine may include control means for cycling the fluid
heating means and fluid cooling means alternately so as to
alternately heat and cool the working fluid and cause reciprocating
motion of the movable wall of the expansion chamber. The control
means may switch the supplies of heating medium and cooling medium
to the fluid heating means and the fluid cooling means in
alternating fashion synchronised with, e.g. in response to, the
movement of the movable wall of the expansion chamber reaching
predetermined points in its reciprocating movements.
[0026] The pressure storage means may be operatively associated
with the movable wall of the expansion chamber. It may include
compression means coupled to the movable wall for compressing a
storage fluid during one of the cycles of the movable wall. It may
include accumulator means for holding pressurised storage fluid at
an elevated pressure and at progressively increasing pressure as
the compression means cycles in response to cyclical movement of
the movable wall of the expansion chamber. Because the accumulator
means stores pressurised storage fluid at an elevated pressure, it
is capable of performing useful work. The accumulator means may be
operatively associated with the controlled work output means to
utilise the stored pressurised storage fluid to perform useful work
by bleeding out the pressurised storage fluid at a controlled
rate.
[0027] The compression means of the pressure storage means may
comprise a movable member such as a compression piston or a
flexible member such as a diaphragm movable within a cylinder.
Where the movable wall and the movable member are both pistons,
preferably the movable member is substantially smaller in diameter
to the movable wall. The effect of the step down ratio of piston
areas is that the working fluid pressure developed in the expansion
chamber is magnified in the pressure storage means. The compression
piston movable in the compression chamber in response to movement
of the movable wall of the expansion chamber, compresses the
storage fluid. The storage fluid being compressed by the
compression means can be supplied to the accumulator means so as to
progressively increase the pressure and volume of the fluid held by
the accumulator means.
[0028] In an alternative arrangement the pressure storage means may
form part of the expansion chamber. The movable wall may separate
the working fluid on one side from the storage fluid on the other.
The movable wall may be flexible as in a diaphragm, or may be in
the form of a piston. The engine may include a battery of expansion
chambers in parallel all adapted to charge the pressure storage
means with pressurised storage fluid. The pressure storage means
may include a movable member that separates the pressure storage
fluid from a counter pressure means, such as a compression spring
or a compressible gas. In the case of a compressible gas, this may
be any suitable gas, preferably non-ignitable, for example,
nitrogen or carbon dioxide.
[0029] The storage or pressurised fluid may be an oil and the
accumulator means may include one or more oil accumulators of
generally known type used for storing hydraulic oil at elevated
pressure for subsequent controlled release.
[0030] The controlled work output system may, for example, include
an hydraulic motor through which the pressurised stored hydraulic
oil can be released in a controlled manner so that the hydraulic
motor can perform useful work. The hydraulic motor may be used to
directly power a hydraulic machine. For example, the work output
system may include a rock crusher used in the mining industry or
other heavy hydraulic machinery. Normally such hydraulic machines
require a costly heavy duty electric motor such as a 400-500 h.p.
motor to operate effectively. The work output system may be coupled
to an alternator or generator to produce electrical energy for
direct utilisation or for charging storage batteries. The storage
fluid, which in the preferred embodiment is hydraulic oil, can be
returned after being released from the hydraulic oil accumulator
means, through the hydraulic motor, to a reservoir. The storage
fluid held at low pressure in the reservoir can be progressively
drawn into the compression means during a return-stroke of the
compression piston, whereas during the compression stroke of the
compression means the supply line to the reservoir is closed and
the hydraulic oil being compressed is supplied to the oil
accumulator means.
[0031] In another aspect there is provided an engine for converting
thermal energy to stored energy for doing work the engine
including:
[0032] (a) a thermal energy converter including an expansion
chamber which is adapted to vary in volume by the movement of a
movable wall forming one pant of the expansion chamber, the movable
wall capable of performing an expansion-contraction cycle;
[0033] (b) a working fluid in said converter compartment which
expands upon being heated and contracts upon being cooled whereby
to displace the movable wall;
[0034] (c) a temperature modifier:
[0035] (i) to heat the working fluid to expand the volume of the
expansion chamber by the displacement of the expansion wall as a
first expansion part of the cycle; and subsequently,
[0036] (ii) to cool the working fluid to reduce the volume of the
expansion chamber and to permit the return of the movable wall as a
second part of the cycle;
[0037] (d) pressure storage means operatively associated with the
movable wall and adapted to deliver pressurised fluid to an
accumulator;
[0038] (e) said accumulator for storing the pressurised fluid at an
elevated pressure; and
[0039] (f) controlled work output means for converting the energy
associated with the pressurised storage fluid to a useful form,
[0040] wherein the engine is adapted to to provide a constant
energy supply to the controlled work output means, irrespective of
the irregularity of the movement of the movable wall.
[0041] Whether the movable ball is in the form of a flexible
membrane, a rigid, axially displaceable member such as a piston or
some other arrangement such as a hinged member, the
expansion/contraction cycle may be described as a stroke cycle from
the beginning of the expansion of the expansion chamber, to its
return to the minimal volume.
[0042] The controlled work output means is preferably capable of
energy conversion at a constant rate, preferably irrespective of
the rate of the stroke cycle or of the rate of the first or second
part of the stroke cycle. For example, the cycle of the movable
wall may be irregular such that stroke cycles may vary in the total
time required to complete a cycle. Moreover, the actual stroke of
the movable wall may be of non-uniform speed. Indeed, typically
there is resistance to the travel of the movable wall during the
first part of the stroke cycle and that resistance is variable over
time. The movable wall may accelerate during its travel through the
stroke as the resistance dissipates. On the other hand, where there
is little or no resistance to the travel of the movable wall during
the stroke such as where an opposed compartment of the expansion
chamber is vented to the atmosphere, the movable wall may be
subject to high initial acceleration, followed by steady
deceleration as the expansion chamber expands, thereby effectively
decreasing the pressure in the expansion chamber. Irrespective of
the rate of the stoke cycle, however, the pressure storage means
may be effective to ensure delivery of sufficient pressurised fluid
to the accumulator means to enable the accumulator means to supply
the controlled work output means with energy at a constant rate, if
required.
[0043] The engine may include a converter including the expansion
chamber on one side of the movable wall and an opposed compartment
on its other side. The opposed compartment may be of variable
volume. Preferably the converter as a whole defines a chamber with
a constant volume such that the variable volume of the expansion
chamber is in inverse relationship to the volume of the opposed
compartment.
[0044] The pressure storage means may include a hydraulic or
pneumatic arrangement, preferably a hydraulic arrangement.
[0045] The engine may include pressure intensification means. In
the pressure intensification means the opposed compartment may
contain at least some of the pressurised fluid. The movable wall
may include a first face in part defining the expansion chamber and
a second face in part defining the opposed compartment. The first
face may be significantly greater in surface area than the second
face to achieve the pressure intensification desired between the
expansion chamber and the pressure intensification means. The
available volume to the pressurised fluid in the opposed
compartment may be reduced by the presence of a column occupying
space between the second face and an aperture in the end wall of
the opposed compartment through which the column may extent. The
column may be any suitable configuration or orientation within the
opposed compartment, provided that it has a constant cross-section
throughout its length or the section of length adapted to travel
through the aperture.
[0046] In another arrangement, the intensification chamber may be
separate from the expansion chamber and the intensification chamber
may house an intensification wall which may vary in construction in
a manner similar to the movable wall. The intensification wall may
be movable to define an intensification chamber compartment of
variable volume. The intensification wall may be operatively
associated with the movable wall. In order to obtain the pressure
intensification desired between the expansion chamber and the
pressure intensification means, the surface area of the movable
wall may be significantly larger than the surface area of the
pressure chamber wall facing the pressurised fluid. The movable
wall and the intensification wall may be connected by a common
shaft extending through the opposed compartment and into the
intensification chamber. The intensification chamber may include
the pressure intensification means.
[0047] The intensification compartment may be selectively in
communication with the accumulator means, whereby to provide the
pressurised fluid to the accumulator at elevated pressures.
Interposed in communication lines between the intensification
compartment and the accumulator may be a valve or a combination of
valves. The combination of valves may include a first one way
outlet valve permitting delivery of pressurised fluid to the
accumulator on completion of each stroke or part thereof. The
combination of valves may also include a one-way inlet valve to
permit return of recycled non-pressurised fluid formerly used when
pressurised to power the work output means. The intensification
compartment, the accumulator and the work output means may form a
closed system in which the pressurised fluid is recycled as
non-pressurised fluid to the intensification compartment.
[0048] The one or more valves may be spring loaded ball and socket
valves as is standard in the art or may comprise any other suitable
valve arrangement effective to perform the required valve
functions.
[0049] The intensification chamber may further include an opposed
intensification compartment on an opposite side of the
intensification wall. The opposed intensification compartment may
be vented to the atmosphere whereby to provide little resistance to
the intensification wall during a stroke cycle. Alternatively, the
opposed intensification compartment may be in communication with a
collector vessel whereby any leakage through seals and the like
associated with the intensification wall may be fed back into a
closed system.
[0050] The pressure intensification means may include return means
for urging the intensification wall and thus the movable wall back
to a return position during the second part of the stroke cycle.
The return means may include a spring. Alternatively, the return
means may include a return chamber containing, for example, a gas
which provides ever increasing resistance as the gas is compressed
by a return piston. The return piston may be operatively associated
with the movable wail and the intensification wall, for example by
means of a coaxial shaft. An opposed return compartment on the
other side of the return piston wall may be vented to the
atmosphere.
[0051] The accumulator means may include one or more closed
containers for housing the pressurised fluid at elevated pressures.
The pressurised fluid may be non-compressible. For example, the
pressurised fluid may be hydraulic oil. Each of the closed
containers may include a movable accumulator wall, for example in
the form of a piston or a flexible membrane. Together with the
accumulator wall, the containers may define a closed compressible
fluid compartment of variable volume. Accordingly, each container
may define a compressible fluid compartment and a non-compressible
fluid compartment. The non-impressible fluid compartment may be in
communication with the work output means.
[0052] The non-compressible fluid may be bled at a regular rate
from the non-compressible fluid compartment at elevated pressure to
drive the work output means. Alternatively, the work output means
coupled to the accumulator may be selectively operable,
intermittently operable or programmably operable whereby to bleed
off pressurised fluid at a predetermined or required time and
rate.
[0053] The work output means may generate electricity. For example,
the work output means may drive an alternator operating, for
example, at 1500 r.p.m. to generate the equivalent of mains power
at 50 Hz to a reliablity of say +/-2%. The work output means may
act as a pump for other fluids, such as water required for domestic
or irrigation purposes or sewage effluent. The work output means
may include an alternator or a generator. The work output means may
charge a battery whereby to store electrical energy.
[0054] The engine may include a second expansion chamber. The
second expansion chamber may be operatively associated with the
first expansion chamber. The second expansion chamber may include a
second movable wall. The second movable wall may be operatively
associated with the first movable wall. For example, the second
movable wall may include a piston having a second shaft. The second
shaft may be operatively connected to the first shaft adapted to
reciprocate along an axis coaxial with the first movable wall. The
first and second shafts may be connected by means of a rocker
arrangement. The first and second shafts may be so arranged as to
reciprocate in opposites directions. The first part of the stroke
cycle of the first movable wall may correspond to a second
complementary part of the stroke cycle of the second movable
wall.
[0055] The rocker arrangement may include locking means to provide
a dwell time in which the first expansion chamber may accumulate
pressure and the first opposed compartment may dissipate pressure
to maximise the power of the stroke of the first movable wall. The
first expansion chamber may pressurise at the same time as the
second opposed compartment pressurises whilst the first opposed
compartment and the second expansion chamber are subject to
dissipation of pressure. Pressurisation may be accomplished by an
evaporator and dissipation of pressure may be accomplished by a
condenser or by respectively circulating through heat exchange
means in the working fluid first heated fluid from the external
heat source and then cool fluid from the external cooling means of
the temperature modifer. After a pre-determined period, the dwell
time may be completed and the power stroke associated with the
first and second expansion chambers executed with a maximum
differential pressure existing between the expansion and opposed
compartments of the respective first and second expansion
chambers.
[0056] The dwell time may be achieved by locking the rocker
arrangement in a particular toggle position at the end of each part
of a stroke cycle. Alternatively, the dwell time may be achieved by
closing one way valves interposed between the pressure
intensification means and the accumulator to effectively lock the
first and second converter walls in a particular position. In
another arrangement, a pressure switch may be used to gauge when
each expansion chamber reaches a predetermined pressure level,
whereby to then activate the cylinder or solenoid holding the
toggle arrangement in position thereby commencing a new part of the
stroke cycle.
[0057] The first and second opposed compartments may be vented and
in communication with air at ambient pressure. The first and second
opposed compartments may be in communication with a collector
vessel in a closed system. The collector vessel may be maintained
at roughly atmospheric pressure and may be effective to return
pressure back to the first and second converter compartments to
reduce the effect of any leakage through seals associated with the
fist and second converter walls.
[0058] The movable wall may be a piston including a shaft adapted
to travel through an aperture in an end wall of the first converter
chamber. The aperture may include seal means to reduce undesirable
leakage of the working fluid from the first converter compartment
through the aperture or the seals associated therewith. The seal
means may include a sleeve to encapsulate the shaft adjacent the
aperture. The sleeve may be concertinaed and may be in the form of
bellows adapted to guard against pressure leakage.
[0059] If required, an alternating current regeneration with active
correction unit to provide a frequency correction interface can be
included in the to interface with the work output system. The unit
may be interposed between the generator or alternator and the work
output system. This is important where the consistency of the power
generated is critical, such as the powering of appliances requiring
an electricity power supply equal to that of mains power, although
for many applications such a unit will be unnecessary. The units
may be effective to regulate the generator or alternator 52 (for
example to maintain at 1500 r.p.m.) and the frequency generated
(for example to maintain at 50 Hz). Such units are commercially
available, for example from Siemens Masterdrive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0060] Possible and preferred features of the present invention
will now be described with particular reference to the accompanying
drawings. However it is to be understood that the features
illustrated in and described with reference to the drawings are not
to be construed as limiting on the scope of the invention. In the
drawings:
[0061] FIG. 1 is a schematic side sectional or view of an engine
and associated apparatus in accordance with a first embodiment;
[0062] FIG. 2A is a schematic side sectional view of an alternative
fluid heat exchange and expansion chamber arrangement;
[0063] FIG. 2B is a schematic side sectional view of another
alternative fluid heat exchange and expansion chamber
arrangement;
[0064] FIG. 3 is a schematic cross-sectional view of a thermal
engine according to a fourth embodiment;
[0065] FIG. 4 is a schematic side view of the fourth embodiment
showing a rocker arrangement with more clarity;
[0066] FIG. 5 is a schematic side sectional view of a thermal
engine including an alternative rocker arrangement according to a
fifth embodiment;
[0067] FIGS. 5A, B and C are schematic sectional side views of a
thermal engine according to a sixth embodiment showing the
expansion chamber in various stages of a stroke cycle;
[0068] FIGS. 6A and 6B are schematic side sectional views of an
expansion chamber according to the first embodiment, augmented by
sealing means;
[0069] FIGS. 7A and 7B are schematic side sectional views
demonstrating the intensification factor in relation to various of
the described embodiments;
[0070] FIG. 8 is a schematic sectional side view of a seventh
embodiment of the invention.
DETAILED DESCRIPTION OF THE DRAWINGS
[0071] Referring to FIG. 1, an engine 1 includes an expansion
chamber 11 and associated heat exchange means 20 for alternately
heating and cooling working fluid in the form of a refrigerant 12
in the chamber 11. The upper wall of the closed chamber 11 is
defined by the piston 13 which is movable vertically within the
chamber 11 in response to changes in pressure of the alternately
heated and cooled refrigerant 12.
[0072] As the temperature of the refrigerant is increased, the
pressure within the chamber 11 increases, substantially forcing the
piston 13 upwards to expand the volume of the chamber 11.
Conversely, if the temperature of the refrigerant 12 is decreased,
the pressure in the chamber 11 decreases.
[0073] The engine 1 includes compression means 30 coupled to the
piston 13 for compressing a storage fluid 32 located within a
compression cylinder 31. The piston 33 which is moveable in the
compression cylinder 31 is coupled by a shaft 35 to the piston 13
in the chamber 11 so as to be moved by movement of the piston
13.
[0074] When compressed by piston 33, the storage fluid 32 flows to
an accumulator means 40 for holding the pressurised storage fluid
32 at an elevated pressure and at progressively increasing pressure
as the compression means 30 cycles in response to cyclical movement
of the piston 13 of the expansion chamber 11.
[0075] Associated with the accumulator means 40 is a controlled
work output system 50 for utilising the storage fluid 32,
representing energy stored as hydraulic fluid pressure, to perform
useful work. Whereas the process of accumulating the stored energy
in the accumulator means may involve irregular and inconsistent
stroke cycles of the piston 13, the stored hydraulic pressure can
be released in a controlled manner. The work output system 50
includes a hydraulic motor 51 coupled to an alternator or generator
52 to generate electrical power, which can be used for example to
charge, electrical batteries 53 or by controlled release of stored
pressurised hydraulic fluid from accumulators, will maintain
constant revolutions of the hydraulic motors coupled to the
generator or alternator 52 thereby producing a fixed frequency and
voltage output to be fed directly to an electrical grid or to a
customer. If required, frequency inverts cm be used to maintain
constant frequency or voltage. An alternating civet regeneration
with active correction unit can be included, interposed between the
generator or alternator 52 and the work output system 50. The units
may be effective to regulate the generator or alternator 52 (for
example to maintain at 1500 r.p.m.) and the frequency generated
(for example to maintain at 50 Hz). It is also possible to have
multiple cylinders with pressure release valves to regulate
hydraulic flow; and to run hydraulic motors directly without
accumulator.
[0076] To further explain, the piston 13 in the expansion chamber
11 as illustrated is at or near the end of its return stroke at the
end of a cooling cycle or about to begin a heating and compression
cycle. The engine 1 includes an hydraulic fluid accumulator 45
which is part of a piston return mechanism 44 operative to return
the pistons 13,33 at the end of a heating and compression cycle
when the storage fluid 32 has been compressed and supplied to the
accumulator means 40. The accumulator 45 is coupled to a piston
return cylinder 46 in which there is a piston 47 coupled to piston
33 of the compression means 30. At the start of and during the
return cycle of the pistons 13,33, the elevated pressure of
hydraulic fluid 48 within the upper portion of the cylinder 46
supplied from the pressure accumulator 45 acts on the piston 47 to
return the pistons 13,33. Conversely, during the compression stroke
the piston 47 is moved upwardly in the cylinder 46 to elevate the
pressure of the hydraulic fluid 48 which is returned through valve
49 to the pressure accumulator 45.
[0077] As a more simple alternative to the piston return means 44,
where possible a compression spring may be provided within the
cylinder 31 acting on the upper face of the piston 33, the spring
being operative to apply downward force to return the piston 33 and
piston 13 during the return cooling stroke or cycle of the engine
1.
[0078] The heat exchanger means 20 provided in the expansion
chamber 11 which is operative to alternately heat and cool the
working fluid 12 has an associated means 22 for cycling the fluid
heating and fluid cooling functions. The cycling means 22 is
illustrated as a two-way valve 23 (and associated timing or
switching mechanism--not shown) which is operative at or about the
point in the cycle illustrated in FIG. 1 to open to allow heating
fluid to enter the heat exchange coil 21 from the heating fluid
inlet 24. The flow of heating fluid from the inlet 21 through the
cycling means 22 and the heat exchange coil 21 raises the
temperature of the working fluid 12 within the chamber 11.
[0079] If the working fluid 12 for example comprises a refrigerant
such as refrigerant type R409a, and the temperature of the
refrigerant was raised to 42.degree. C., the pressure of the heated
refrigerant would be 935.9 kPa (137 psi). If the diameter of the
piston 13 is, say, 304 mm (12 inches) the surface area of the
piston would be 113 square inches providing a force of 15494 lbs
acting on the lower fee of the piston 13. With the piston 13
coupled as shown in FIG. 1 to the piston 33 of say, about 4 inches
diameter, the piston 33 can create an hydraulic force of perhaps
2000 psi to act on the storage fluid 32 in the cylinder 31.
[0080] When the pistons 13 and 33 have reached the tops of their
strokes and the storage fluid 32 has been expelled from the
cylinder 31 through line 36 to the accumulator means 40, various
valves can be switched as required to commence a cooling return
stroke. In particular, the valve 37 in output line 36 can be
closed, and the valve 57 through which low pressure hydraulic fluid
can be returned to the cylinder 31 is opened to allow hydraulic
fluid from storage reservoir 55 to flow through line 56 to refill
the cylinder 31 as the piston 33 moves downwardly. To promote or
assist the return of the pistons 13,33 in their respective
cylinders 14,31, pressurised hydraulic fluid in accumulator 45 can
flow through valve 49 to the piston return cylinder 46 to urge the
piston 47 downwardly. At substantially the same time, the two way
valve 23 is switched to pass cooling fluid from inlet 26 into the
heat exchange coil 21 so as to cool the refrigerant 12 within the
chamber 11. If the refrigerant is K409a, the temperature of the
refrigerant 12 is reduced to 18.degree. C. and the pressure drops
to 418.9 kPa (61.57 psi). When pistons 13,33,47 have reached the
bottoms of their strokes, the valve 57 is closed because cylinder
31 is now charged with new hydraulic fluid, valve 37 is opened, and
two-way valve 23 is switched again to admit heating fluid to the
heat exchange coil 21.
[0081] The heating and cooling fluids supplied respectively through
inlets 24,26 may be obtained from any convenient sources. Because
the temperature to which the refrigerant 12 is heated can bc
relatively low (42.degree. C. in the example), the possible sources
of heating fluid can include solar energy fluid heaters, waste gas
emissions from vehicles, generators, industrial plants and
equipment, geothermal sources etc. The exhaust gases may be passed
through the heat exchange coil 21 directly. Alternatively, water
heating coils can be passed in heat exchange relationship to
exhaust pipes, chimneys, or the like caring the heated gases so
that the water is heated thereby and the heated water is used as
the heating fluid passing through the coil 21 in the engine. Of
course, the hot gases themselves can be utilised directly as the
heating fluid as shown if FIG. 2A. Likewise, the cooling fluid
passed through the coil 21 during the cooling return cycle can be
any suitable or conveniently available cooling fluid, such as cool
or cold water from any convenient available source, such as natural
or artificial streams, ponds, or other bodies of water.
[0082] In the modified embodiment illustrated in FIG. 2A, the heat
exchange means 120 is substantially separate from the chamber 11
although the working fluid 12 is in direct communication with the
chamber 11. In this embodiment, the heat exchange means 120
includes a thermal fluid chamber 121 having an inlet 124 through
which heating fluid and cooling fluid are alternately introduced
under control of a cycling means such as the cycling means 22 in
the embodiment of FIG. 1. The heating fluid and cooling fluid pass
through the thermal fluid chamber 121 and exit through outlet 125.
The chamber 121 is substantially totally enclosed within an
insulating jacket 126 to reduce thermal losses through the outside
walls of the chamber 121. Also the outside wells of the chamber 121
may be relatively thin material to reduce thermal load losses in
alternately heating and cooling the walls. As well as thin metallic
walls, the walls could be non-metallic. e.g. ceramic or alumina
material to have low heat conductivity.
[0083] Located centrally within the chamber 121 is a side chamber
127 of the expansion chamber 11, the side chamber 127 being in
communication with the expansion chamber 11 so as to be filled with
the working fluid 12. The side chamber 127 has highly heat
conductive walls 128 so that heat from heating fluid passing
through chamber 121 from inlet 124 to 125 is rapidly supplied to
the working fluid 12 within the chamber 127. This in turn will
cause the desired rise in pressure in the expansion chamber 11 to
move the piston 13 during the heating and storage fluid compression
stroke. Conversely, when cooling fluid is being passed through
inlet 124, through the chamber 121, and out of outlet 125, the
heated working fluid 12 in the side chamber 127 rapidly yields up
heat through the walls 128 to the cooling fluid to reduce the
pressure in the expansion chamber 11 acting on the underside of the
piston 13 during the cooling return stroke.
[0084] It will be seen that the engine is relatively simple in
operation and many of the components can be readily available
existing types of equipment. The construction, assembly,
installation, operation and maintenance of the engine and
associated equipment can be relatively simple, and operators and
maintenance personnel need not be highly educated and trained
personnel since the technology is relatively simple.
[0085] In FIG. 2B an alternative engine 60 to the embodiment shown
in FIG. 1 is shown. The engine 60 includes a plurality or battery
of thermal conversion cylinders 61a-f including corresponding
expansion chambers 62a-f. Instead of the expansion wall of each
expansion chamber 62a-f being a rigidly formed piston as in FIG. 1,
the expansion wall is a a flexible bladder or membrane 63a-f.
Instead of having separate pressure storage means, the thermal
expansion cylinders 61a-f play a duel role of providing the
expansion chamber 62a-f as well as the pressure storage means 64a-f
on the opposed side of the flexible membrane 63a-f in the thermal
expansion cylinders 61a-f. By heating and cooling the working fluid
inside the accumulator/converters 61a-f, external condenses,
evapourators, and pumps are not necessary in this arrangement. The
pressure storage means 64a-f contains storage fluid in the form of
hydraulic fluid which is in communication, via valves 65a-f, to
accumulator means 66a. The storage fluid in accumulator 66a is
maintained at an extremely high pressure of about 3000 p.s.i and is
continually bled at a low late whereby to power a motor M. The
storage fluid is recycled via return accumulator 66b which
maintains the storage fluid at about 250 p.s.i. to provide a return
stroke facility for the engine 60. The accumulators 66a,b have a
similar flexible membrane 67a,b through which a second compartment
68a,b contains variously pressurised nitrogen gas. The accumulator
oil refill should be automatic due to there being a constant
cooling fluid temperature whereby to produce maintain the return
fluid in accumulator 66b at about 250 p.s.i. In contrast, the
storage fluid in accumulator 66a is maintained consistently at a
pressure of about 3000 p.s.i. The expansion chambers 62a-f are
supplied with alternating hot and cold fluid by lines 69a and 69b,
respectively, interposed a plurality of valves 70. The hot fluid
may alternatively be preheated via an optional route 71 or, if a
ready sufficently hot fluid source is available, this available hot
fluid may be used directly as represented by lines 72. It is
clearly preferable from a cost viewpoint to utilise any available
direct hot fluid source 72. The hot fluid sources 71,72 can be
pressure switched. For example, when the working fluid in one of
the expansion chambers 62a-f reaches a predetermined pressure, the
pressure switch ma) case the hot fluid supply 71,72 to switch to
the next cylinders 61a-f. The engine also includes a cool fluid
source 73. The cool fluid source 73 may be series connected to an
existing plant where available. It will be appreciated that the
more expanding working fluid pressure switched condensers,
ultimately the better the flow pulse supply of the storage fluid
from the pressure storage means 64a-f to the accumulators
66a,b.
[0086] The operation of the valves 70 are controlled, either by
pressure switching as mentioned above, or by a computer system
timed to correspond to the stroke cycle of each of the accumulator
converters 61a-f. The pressure of the working fluid may vary
between about 200 p.s.i. at the end of the cooling part of the
stroke cycle to 820 p.s.i. at the end of the heating part of the
stroke cycle. The accumulation of pressure in the storage fluid in
the accumulator 66a is thus able to be maintained at about 3000
p.s.i. due to the additive effect of the combination of the
operation of the accumulator/converters 61a-f and the rate of
bleeding off of the storage fluid to power the motor M.
[0087] Turning to FIG. 3, tere is shown a thermal energy converter
140, a temperature modifier 150, a pressure intensification moms
160 and a rocker arrangement 170, being components of an engine
140a for converting thermal energy. The accumulator 40 and
controlled output means 5 of the engine 140a are as described in
relation to the embodiment of FIG. 1.
[0088] The thermal energy converter 140 includes a first expansion
chamber 141 and a second converter chamber 142. The first converter
chamber 141 houses a piston 143 adapted for linear reciprocal
travel within the first converter chamber 141. A first shaft 144,
extends axially either side of the first piston 143, is fixed
relative to the piston 143 and extends through apertures in the
opposed ends of the cylindrically shaped first converter chamber
141. The piston 143 divides the first converter chamber 141 into
two compartments, the first expansion compartment 145 which varies
in volume in inverse relation to the volume of a first opposed
converter compartment 146 in the first converter chamber 141.
[0089] Co-axially fixed to the first shaft 144 is a first pressure
piston 161 housed in a first pressure chamber 162. A similar mirror
image arrangement may be seen in relation to second pressure
chamber 166. The first pressure chamber 162 defines, together with
the first pressure piston 161, first pressure compartment 163 and
first opposed pressure compartment 164. First opposed pressure
compartment 164 is vented to the atmosphere. First opposed pressure
compartment 163 is in communication with the accumulator means 40
described in relation to FIG. 1 via a pair of inlet/outlet valves
165.
[0090] The temperature modifier 150 includes a condenser 151 and an
evaporator 152 in communication with the first and second converter
chambers 141, 142 via separate lines: condenser line 153 and
evaporator line 154. The inline condenser 151 includes a coil which
extends through cool fluid, such as water from a local stream or
another cool water source which flows to cool the working fluid in
condenser line 153. The evaporator 152 also includes a coil through
which hot fluid, such as hot water or gas from a local source,
flows to heat the working fluid in evaporator line 154. The working
fluid is refrigerant AZ20. Inline evaporator and condenser valves
155, 156 are located inline the condenser and evaporator lines 153,
154.
[0091] The second converter chamber 142 and the second pressure
chamber 166 are reflectively the mirror image of first converter
chamber 140 and first pressure chamber 160, respectively.
Accordingly, extending through the second converter chamber 142 and
into the second pressure chamber 166 is a second shaft 147 attached
at a second end to a rocker 171. Similarly, the lower end of the
first shaft 144 is pivotably attached to a first end of the rocker
171. In the lower portion of FIG. 3, the rocker arrangement 170 is
shown and is shown in greater detail in FIG. 4. The rocker
arrangement 170 includes rocker 171 adapted to pivot about pivot
point 172. The pivoting of rocker 172 is controlled by a co-axially
pivotal toggle bracket 173 whose pivoting action is controlled by
an over-centre arrangement 174 which, together with a pair of
hydraulic cylinders 176 pivotally extending from a base 175 to an
end each of the toggle 173, enables the rocker arrangement to be
locked into position until the pair of cylinders 176 are again
activated. Screw bolts 177 are threaded into the base 175 to
provide adjustable stops limiting the extent of travel of the
over-centre 174. By this mechanism, a dwell time is achieved for
the engine of FIG. 3 or 4 whereby to permit pressure build up of
the working fluid in complementary compartments of the first and
second converter chambers 141, 142. This optimises the pressure
differential between the first and second expansion compartments
and the first and second opposed converter compartments to maximise
the power strokes associated with each of the first and second
converter chambers. Note that the power stroke in the arrangement
shown in FIG. 3 is effected in both the first and second converter
chambers 141, 142 simultaneously, whereas in the arrangement shown
in FIG. 4, she first and second opposed compartments 136 are vented
to the atmosphere or to a pressure collector, whereby each
converter chamber provides a power stroke every alternate part of
the stroke cycle.
[0092] Whereas the arrangement of FIG. 3 is considered to produce
greater power compared to that of FIG. 4, it is also less efficient
in its use of the available energy as the resistance provided by
the opposing compartment during a power stroke must overcome the
ambient pressure of the refrigerant to effect the power stroke.
However, both chambers may perform the power stroke at the same
time.
[0093] With particular reference to FIG. 3, in a first part of the
stroke cycle, first expansion compartment 145 is cooled to lower
the pressure to the ambient pressure of the refrigerant, that is
about 200 psi, whilst dwell time achieved by locking rocker
amazement 170 permits the pressurisation of the first expansion
compartment 145 as well as the corresponding second opposed
converter compartment 148. This is achieved by opening the
evaporator valves 156 to the second opposed converter compartment
148 and the first expansion chamber 145 and closing the condenser
valves 155 so that the working fluid achieves pressures of between
500 and 800 psi in these compartments 145, 148, whereas the first
opposed converter compartment 146 and a second expansion
compartment 149 are cooled by exposure of the working fluid in line
153 to the cooling fluid of the condenser 151. Evaporator line 154
and condenser line 153 both include small piston pumps adapted to
circulate the working fluid through lines 153,154. The piston pumps
(not shown) require minimal energy and may therefore involve a
separate feed line from the accumulator or be driven by a battery
charged by the work output means or directly from generator or
alternator output.
[0094] In FIG. 4 it is clearly shown that the first and second
converter chambers are pivotable about fist and second pivot points
178, 179 to ensure that the first and second shafts 144, 147 follow
the curved path caused by their pivotal attachment to the rocker
171.
[0095] In FIG. 5 there is shown a double expansion double rocker
arm arrangement 80 comprising a double rocker arm arrangement 81,
expansion means 90, accumulator means 100 and heating/cooling means
110.
[0096] The double rocker arm arrangement 81 includes a large rocker
arm 82 coaxially and pivotally associated with a second smaller
rocker arm 83. The large and small rocker arms 81, 82 are adapted
to pivot in opposed relative relationship about their common axes
of rotation 86. The large rocker arm 82 includes a pair of opposed
ends, a first end 85 and a second end 84, whereas the small rocker
arm 83 includes a first end 88 opposed to a second end 87. In
operation, the respective first ends 84, 87 reciprocally rotate in
opposite directions. Similarly, the respective second ends 85, 88
reciprocally rotate in opposite directions relative to one another.
The first large end 85 is pivotally engaged to a pair of piston
arms 91, 101 rigidly connected to respective pistons 91A, 101A. The
piston 91A reciprocates in a cylinder 91B. The piston arm 101 is
rigidly connected to a piston 101A which operatively reciprocates
in an accumulator cylinder 101B.
[0097] On the opposition second end 84 of the large rocket am 82 a
pair of piston arms 92, 102 are pivotally mounted and are rigidly
connected to corresponding pistons 92A and 102A. Piston 92A is
operative to reciprocate in an expansion cylinder 92B whereas
piston 102A is positioned to reciprocate within an accumulator
102B. Similar complementary thermal converter cylinder and
accumulator cylinder arrangements are shown in the illustration of
FIG. 5 whereby there is a provided a pair of thermal converter
cylinders 93 and 94 pivotally connected by their respective pistons
93A and 94A to the first and second ends 88, 87, respectively, of
the smaller rocker arm 83. Furthermore, accumulators 103, 104 are
pivotally connected to the small rocker arm 83 at its respective
first and second ends 88, 87 via pistons 103A and 104A. In
operation, it can be seen that, as illustrated, hot working fluid
is admitted to converter 94 from an evaporator 110A to perform a
power stroke in which the piston 94A forces the second small end 87
downwardly. This downward movement causes the piston 104A to
compress the storage fluid 104B in the accumulator 104. This
pressurised storage fluid 104B is released by a valve 104C to final
accumulation means such as accumulator means 40 described with
reference to FIG. 1. On the return stroke, the heated working fluid
from converter 94 is delivered to converter 92B causing a downward
stroke of the second end 84 of the large rocker arm 82, in turn
causing a downward stroke of piston 102A in accumulator 102B to
provide a further charge of pressurised storage fluid in the form
of hydraulic oil via valve 102C. During this return stroke, the
working fluid in converter 94 is cooled to cause piston 94A to
withdraw upwardly dragging the smaller rocker arm 83 and the piston
104A upwards, whereby recycled non-pressurised hydraulic oil 104B
may be admitted to accumulator 104 via a oil inlet valve 104D.
[0098] It can be seen that the stroke length of the pistons 93A,
94A, 103A, 104A, are the same and the piston cross sectional areas
are also the same. Conversely, whilst the respective volumes of the
accumulators 91B, 93, 94, 92B are the same whereby to admit the
transfer of heated working fluid from accumulators 93, 94
respectively to accumulators 91B, 92B, the stroke lengths of the
pistons 91A, 92A, 101A, 102A are much shorter than the stroke
lengths of pistons 93A, 94A, 103A, 104A, the cross sectional areas
of pistons 91A, 92A are significantly greater than the cross
sectional areas of pistons 101A, 102A to provide a pressure
intensification factor. For example, the stroke length of piston
93A may be 22 inches (55 cm) and the cross sectional area of piston
93A, 6 inches (15 cm). Conversely, the stroke length of piston 91A
may be about 10 inches (about 25 cm), its diameter about 4 inches
(about 10 cm), whereas the diameter of piston 101A may be about 5
inches (about 13 cm). By this arrangement, a storage fluid pressure
of, for example, 3000 p.s.i. can be maintained. The pressure of the
working fluid in each expansion means can vary between 820 p.s.i.
and 200 p.s.i.
[0099] In FIGS. 5A, B and C there is shown an alternative
arrangement in which the first and second opposed converter
compartments 180, 181 are vented to the atmosphere or are in
communication with a pressure collector vessel which is adapted to
feed escaped pressure back into the working fluid system 182. In
this regard, leakage is likely to occur through the annular seas
183 about the pistons 184, 185. Shown in FIGS. 6A and B are bellows
190 which are in the form of concertinaed sleeves surrounding
sections of the shaft 191 either side of the converter chamber 192.
The bellows 190 may be in communication with pressure collector
vessel (not shown) to reduce pressure loss from the overall
system.
[0100] Referring to FIGS. 7A and B, the schematic diagrams
illustrate how pressure intensification is achieved in the
transition from the expansion compartment corresponding to a
relatively large Area "Y" to the smaller piston head of the
pressure intensification means (Area "X"). In FIG. 7B, a central
cylindrical column 193 is located on the single piston head 194 and
the pressure chamber 195 corresponds to the opposed converter
compartment, such that the thermal energy converter and the
pressure intensifier are housed in a single chamber. In each
example shown, a pressure intensification factor of 3 is achieved
by different thermal engine converter/pressure intensifier
combinations.
[0101] In FIG. 8 there is shown a generator arrangement comprising
a thermal energy converter 200 interposed between a pair of
pressure chambers 201, 202, whereby ach part of the power stroke
cycle of converter 200 alternately charges a different pressure
chamber 201, 202. In such an arrangement, provision of a dwell time
is desirable to achieve optimum pressure differential between
converter compartments 203, 204.
[0102] There are obviously many variables in the arrangement of the
engine that affect performance parameters including the respective
piston areas, the strokes of the respective pistons, whether one
directly couples pistons as shown using shaft 35 or whether
indirect coupling, e.g. through leverage to magnify pressures, is
used, the number of cycles of heating and cooling achievable, the
temperatures to which the working fluid is heated and cooled, and
the nature of the refrigerant working fluid. It is also possible to
have multiple expansion chambers 11, multiple associated heat
exchange means 20, and multiple compression means 30 operating out
of phase with each other in parallel so that substantially
continuous flow of pressurised hydraulic fluid occurs instead of
the intermittent flow to the accumulator means 40 that occurs in
the single cycle engine 1 illustrated in FIG. 1. The pressurised
storage fluid 32 being output in line 36 is preferably passed
directly to the hydraulic accumulators 41, 42 so that these
accumulators store the hydraulic fluid at high pressure. The
hydraulic fluid can be released in a controlled manner at a
constant flow rate to the output system 50. It will be seen also
that the engine can use heating and cooling sources available at
many places around the world including over great ranges of
climates since it is the temperature differential between the
temperature to which the working fluid is heated and to which it is
cooled that determines the possible work output rather than the
absolute values of those temperatures. Also, the engine can be
particularly environmentally acceptable since combustion of fuel is
not necessary for its operation and/or sources of heat that is
currently being wasted or lost (e.g. in heated exhaust from engines
and industrial plant and equipment) can be utilised to perform
useful work.
[0103] It is to be understood that various alterations,
modifications and/or additions may be made to the features of the
possible and preferred embodiment(s) of the invention as herein
described without departing from the spirit and scope of the
invention.
* * * * *